In motor vehicles with a drivetrain having an internal combustion engine and, separable by means of a friction clutch, automated gearboxes, for example automated shift gearboxes or double-clutch gearboxes with two component drivetrains—also referred to as component gearboxes—which can be connected to the internal combustion engine by means of, in each case, one friction clutch, a starting gear—for example the first or the second gear—is engaged preferably before coming to a stop in order to be able to quickly drive off again or continue driving. Here, the engagement of a starting gear is often carried out as an overrun downshift, which can result in shift shocks and shift noises which impair driving comfort.
To reduce such an impairment, the downshift may take place at a time at which the motor vehicle has slowed to a considerable degree or is already at a standstill. If, in such a situation, it is sought for example to drive off quickly again (change of mind), the delayed downshift can delay the starting process. Alternatively, the shift itself may be delayed such that the synchronization of the starting gear can be carried out with relatively low synchronization forces and therefore with a relatively minor shift jerk and low noises. This undesirably delays the shift.
Also possible is a method for the synchronization of the starting gear in which the rotational speed of the crankshaft of the internal combustion engine is increased with the friction clutch closed and the shift points are changed. Here, the drivetrain behaves in a way that a driver must become accustomed to, with increasing rotational speed of the internal combustion engine when coming to a stop. Furthermore, fuel consumption is increased. Disadvantages here are the somewhat unusual behavior (engine rotational speed increases when coming to a stop) and the increased fuel consumption.
It is therefore an object of the invention to improve a method for controlling a drivetrain with an automated double-clutch gearbox in particular with regard to a comfortable synchronization of a starting gear before the motor vehicle comes to a stop.